The vibrational energy levels in acetylene. III. 12C2D2

We have performed the rovibrational analysis of the absorption spectrum of (C2D2)-C-12 between 5150 and 8000 cm(-1), recorded by Fourier transform absorption spectroscopy, and between 12 800 and 16 600 cm(-1), recorded by intracavity laser absorption spectroscopy. Respectively 10 and 9 bands are reported for the first time in each range. Improved or new rovibrational parameters were obtained for 34 vibrational levels altogether. The vibrational energies we obtained, together with those reported in the literature, were taken into account to model the vibrational energy pattern in (C2D2)-C-12((X) over tilde(1) Sigma(g)(+),). The analysis was performed in successive steps, inferring each time suitable parameters. The 44/55, 11/33, 12/33, and 1/244 quartic order anharmonic resonances were introduced during the procedure. They altogether define vibrational clusters which are characterized by only two dynamical constants of motion, N-s,= V-1+V-2+V-3 and k=l(4)+l(5). (C) 1998 American Institute of Physics. [S0021-9606(97)03044-4].